Field of the Invention
This specification relates to a display device that outputs a three-dimensional (3D) image including a virtual object and a controlling method thereof.
Discussion of the Related Art
The augmented reality (AR) technology, which corresponds to a combination of a real object and a virtual object, allows a user to view a virtual image along with a real image, so as to provide the user with a sense of reality and supplemental information at the same time. For example, when the user's surroundings are seen through a camera, which is equipped in a smart phone, the real image of the user's surroundings is displayed along with an augmented reality image, such as a location, a telephone number, and so on, of a shop (or store) located near-by, in the form of a stereoscopic image (or three-dimensional (3D) image). The augmented reality technology may be applied to a wearable computing device (or a wearable display device). Most particularly, a display that is worn on the head, such as a head mounted display, displays an environment that is actually seen (or viewed) by the user, wherein the displayed environment is being overlapped in real-time with a virtual image or text, and so on, thereby providing the user with an augmented reality.
The augmented reality image also provides a virtual object, which is provided through a 3D image. The virtual object being provided through the 3D image has a depth within the augmented reality image. Herein, a depth has an axis along a direction moving further away based upon the perspective of the user.
The user may select a virtual object through an input object, such as the user's finger, from an augmented reality image. However, a distance of a virtual object recognized and view through the user's perspective, i.e., a depth of the virtual object is merely an illusion caused by binocular parallax of the user and does not correspond to an object actual object located at a specific distance. And, therefore, an error may occur between a distance of a virtual object that is recognized by the user and a depth at which the virtual object is located.
FIG. 1 illustrates a reference diagram showing selection accuracy respective to a depth of a virtual object in a 3D image.
Referring to (a) of FIG. 1, arbitrary virtual objects 11, 12, and 13 are shown in a three-dimensional (3D) image. A depth of a virtual object, which indicates a distance level from which the corresponding virtual object is spaced apart from the user's perspective (or eye-gaze), exists in the 3D image. The depth becomes smaller as the virtual object comes near the user's perspective, and the depth becomes larger as the virtual object is placed further away from the user's perspective. Therefore, it will be understood that the virtual object assigned with reference numeral 11 has the smallest depth. And, it will also be understood that the virtual object assigned with reference numeral 13 has the largest depth, and the virtual object assigned with reference numeral 12 has the middle-level depth.
Referring to (b) of FIG. 1, an accuracy respective to the depth corresponding to when the user has selected a virtual object is illustrated. As shown in the drawing, as the depth is smaller based upon a specific depth ‘a’, and as the depth is larger based upon a specific depth ‘a’, the level of accuracy becomes lower. The specific depth ‘a’ corresponds to a location point where a distance of the virtual object, which is recognized by the user due to the binocular parallax, coincides with an actual depth at which the virtual object is located within the 3D image. The specific depth ‘a’ is generally close to a point that is reached by a tip of the user's hand, when the user naturally stretches out his (or her) hand.
In order to overcome such errors, a method for displaying a guide image configure to help selecting an object existing within the same plane in a virtual image is disclosed in the published U.S. Patent Application No. US 2010/025352. However, the method disclosed in the above-mentioned related art document, a guide image refers to the provision of another virtual object, and, by providing the user with an excessive number of virtual objects, a complicated image may be displayed to the user. Therefore, a method for resolving such problems is needed.